asp.net頁面彈出對話方塊

------建立MessageBox.cs類------
using System;
using System.Text;

namespace Project.Library
{
    /// <summary>
    /// MessageBox 顯示訊息提示對話方塊。
    /// </summary>
    public class MessageBox
    {
        public MessageBox()
        {
            //
            // TODO: 在此處添加建構函式邏輯
            //
        }
        /// <summary>
        /// 顯示訊息提示對話方塊
        /// </summary>
        /// <param name="page">當前頁面指標，一般為this</param>
        /// <param name="msg">提示資訊</param>
        public static void Show(System.Web.UI.Page page, string msg)
        {
            page.RegisterStartupScript("message", "<script language='javascript' defer>alert('" + msg.ToString() + "');</script>");
        }

        /// <summary>
        /// 控制項點擊 訊息確認提示框
        /// </summary>
        /// <param name="page">當前頁面指標，一般為this</param>
        /// <param name="msg">提示資訊</param>
        public static void ShowConfirm(System.Web.UI.WebControls.WebControl Control, string msg)
        {
            //Control.Attributes.Add("onClick","if (!window.confirm('"+msg+"')){return false;}");
            Control.Attributes.Add("onclick", "return confirm('" + msg + "');");
        }

        /// <summary>
        /// 顯示訊息提示對話方塊，並進行頁面跳轉
        /// </summary>
        /// <param name="page">當前頁面指標，一般為this</param>
        /// <param name="msg">提示資訊</param>
        /// <param name="url">跳轉的目標URL</param>
        public static void ShowAndRedirect(System.Web.UI.Page page, string msg, string url)
        {
            StringBuilder Builder = new StringBuilder();
            Builder.Append("<script language='javascript' defer>");
            Builder.AppendFormat("alert('{0}');", msg);
            Builder.AppendFormat("top.location.href='{0}'", url);
            Builder.Append("</script>");
            page.RegisterStartupScript("message", Builder.ToString());

        }
        /// <summary>
        /// 輸出自訂指令碼資訊
        /// </summary>
        /// <param name="page">當前頁面指標，一般為this</param>
        /// <param name="script">輸出指令碼</param>
        public static void ResponseScript(System.Web.UI.Page page, string script)
        {
            page.RegisterStartupScript("message", "<script language='javascript' defer>" + script + "</script>");
        }
    }
}
------cs頁面調用------
Project.Library.MessageBox.Show(System.Web.UI.Page, "我是對話方塊。");